Some utility rate increases linked to the shutdown of the San Onofre nuclear plant would be put on hold if the California Public Utilities Commission approves a newly proposed plan.

In late October, the agency is scheduled to consider whether to withhold reimbursement of $69.4 million to San Diego Gas & Electric for replacement power purchased from when the plant became idled in January 2012 until its permanent retirement in June. Such a withholding would limit SDG&E rate increases to $118 million for covering standard power-procurement costs this year, according to a statement from the commission.

San Onofre was closed because of rapid wear on steam generators that were replaced in 2010 and 2011. The heat exchangers were supposed to extend the life of the plant, but the premature wear affected thousands of generator tubes carrying radioactive water.

The commission is conducting an investigation to determine who should pay for the San Onofre expenses since the facility was shut down. SDG&E, which owns a 20 percent stake in the facility, seeks to recover $808 million in assets from customers — on top of costs for attempted repairs and initial replacement power.

Eventually, the commission plans to consider whether it is justified and reasonable for utility customers to shoulder costs associated with the plant’s breakdown and permanent closure. The agency could call for a rebate and shift some expenses to utility stockholders.

Edison owns roughly 78 percent of San Onofre, and the city of Riverside owns less than 2 percent.

“I want to assure customers that they will not pay twice for the costs associated with the outage at San Onofre while the CPUC investigation comes to its conclusion,” Commissioner Mike Florio, who is overseeing the cost-liability investigation, said in a statement. “This is a question of fundamental fairness to customers.”